Mexico City (AFP) – Mexico is studying a request by the United States to put armed US air marshals on cross-border flights, the head of Mexico’s National Security Commission said on Tuesday.

“No decision has yet been taken on the matter,” Renato Sales told the Televisa network.

But the proposal was for US federal marshals to be on “strictly commercial and North American (US) flights… not on Mexican airlines,” he said.

Sales said the request was first made three years ago, as part of heightened US security concerns following the September 2001 terror attacks in the United States.

The idea was for US air marshals to sit on planes dressed as ordinary passengers, but armed with electric stun pistols and ready to counter any safety threat on board.

The US government has expressed worries about the level of insecurity in Mexico, in particular a surge in violence linked to drug cartels. Under President Donald Trump, it has also focused on stemming the flow of migrants entering the United States illegally.